dom0 memory and HVM

[Bryan Vyhmeister <netbsd%bsdjournal.net@localhost>]

I'm trying to determine how much memory is reasonable for my NetBSD
5.1_RC2 dom0 when I am going to be running a number of HVM domU
systems. I have it running with 256MB now but I see the qemu-dm
processes taking a lot of memory and top indicates very little free
memory (somewhere between 30MB and 2MB most of the time).

I am currently running a NetBSD 5.1_RC2 dom0 with xen 3.3.2 and this
is all running on a Mac mini 2.0GHz Core 2 Duo with 3 GB of RAM. I
have allocated 256MB to dom0 and I have 512MB for each of two HVM domU
systems (OpenBSD in this case). I intend to create several more HVM
systems and I'm just trying to get an idea of how much memory I should
be allocating to dom0. I tried setting the dom0 memory to 512MB and
then 1024MB but the free memory in top stays about the same as with
256MB. I also recognize that top is not very accurate under xen.

I guess I am just asking for some real world dimensioning examples
with HVM domU systems. Does anyone have any thoughts? Thank you!

Bryan